a. Field of the Invention
This invention relates to a multiple-glazed window containing an integral assembly for controlling the amount of daylight passing though the window into a room. In particular, the invention relates to a window having a peripheral frame enclosing inside and outside glass panes that are substantially parallel and define a space between them which is preferably sealed and in which the light-control assembly is mounted.
b. Background Art
Double-pane windows containing motorized venetian blinds as light-control assemblies have been described in U.S. Pat. Nos. 4,723,586 and 4,979,552. Such windows have satisfied most light-control requirements. In addition, the mere positioning of a venetian blind within the space between two glass panes in a window has long been known to reduce heat losses by radiation through the window to an extent approaching those of windows with triple panes.
Notwithstanding this, the increased use of computer monitors in office buildings has presented additional demands on windows and their associated light-control assemblies for providing protection against the glare from sunlight, without totally eliminating daylight illumination within such buildings. Blocking such glare by closing the window blinds has often diminished the level of illumination in offices below acceptable limits, but increasing the use of artificial illumination, such as electric lighting, has also been objectionable from an environmental point of view.
Anti-glare venetian blinds have also been previously described. For example, in European patent 0,303,107, an anti-glare venetian blind is provided with slats: which are upwardly concave, which have their inner longitudinal edges (facing towards the room) as high or higher than their outer longitudinal edges (facing away from the room), which are mirrored on at least their topsides and retro-reflecting on their undersides, and the spacing and position of which are so selected that the light passes through them mostly into an angular region above the horizon. In European patent application 0,606,543, an anti-glare blind is provided with slats which are: upwardly concave, mirrored on their topsides and at least partially perforated. Although these blinds appear to be able to guide light towards the ceiling of a room and avoid glare, they are not adapted to allow some sunlight to enter the rest of a room. In this regard, it would be desirable, on sunny days, to be able to block or inhibit heat and glare from entering the rest of the room, without blocking daylight illumination entirely from the rest of the room.